Field of the Invention
This invention relates to color cathode ray picture tubes, and is addressed specifically to an improved cataphoretic process for manufacturing color cathode ray tubes. The process is applicable to the manufacture of conventional color picture tubes; that is, tubes having a curved faceplate and a correlatively curved shadow mask, and in the manufacture of color tubes having shadow masks of the tension foil type mounted in association with a flat or substantially flat faceplate. Color tubes of various types can be screened by the process, including those used in home entertainment television receivers. The cataphoretic process according to the invention is particularly valuable in the manufacture of medium-resolution, high-resolution, and ultra-high resolution tubes intended for color monitors. To meet the requirement for high resolution and high definition in such tubes, the phosphor elements must be extremely small and well defined. The problems inherent in screening such tubes is pointed up by the fact that there are more than five million such elements deposited on the screen of an ultra-high resolution color tube. The depositing of so many elements is at the limit of capability of conventional photoscreening processes. The cataphoretic process also offers an economical benefit in that it is much less wasteful of the expensive phosphors used in color screening.